I have a few pre-amps that have "died" over the years. Both still show voltage from the injectors, but neither show any boost in signal.

Is there a basic troubleshooting guide for the electronics in these things? Something that tends to go bad with electric spikes or lightning? I see no signs of burning or failure on the boards... mosfets seem fine.

I have a few pre-amps that have "died" over the years. Both still show voltage from the injectors, but neither show any boost in signal.

Is there a basic troubleshooting guide for the electronics in these things?

There is no basic troubleshooting guide for the electronics in preamps.
Even if you found a bad part, could you remove and replace a tiny surface mount component?

There are external tests you can make like measuring the current to the preamp, measuring the voltage at the preamp when it is connected, and measuring its gain. If it fails those tests, replace the preamp.

Gotcha. I've replaced plenty of parts on PC/videocard motherboards, so I could probably do ok with what I see on these. What could it hurt to try, ya know? I'd need to dust off the extra hands/magnifier, probably!

I was just curious if you typically started with the power, or the signal side... or if spikes caused X to go bad before Y. I'll see what I can dig up, and test what I can. Thanks.

The LNA-200 appears to amplify UHF and VHF separately. Q2 is the UHF amp. Q1 is the VHF amplifier. While both could be bad, if the amp works in VHF but not UHF, change only Q1. If it works on UHF but not VHF, change only Q2.